1. Field of the Invention
The present invention relates to an image processing device and image processing method for coding image data, which is divided by a given pixel count into macroblocks, on a macroblock-by-macroblock basis.
2. Description of the Related Art
For image data obtained by imaging a human subject, the skin-colored area such as the face attracts the viewer's attention. In the case of image data, therefore, subjective image quality can be improved effectively by improving the image quality of the skin color of the face or other parts of the body.
In order to achieve improved subjective image quality, the existing image processing devices have typically performed skin color detection and assigned a higher bitrate to those macroblocks detected to contain the skin color, thus providing improved image quality.
However, if the skin color is detected in many areas of the screen, a higher bitrate is assigned to the macroblocks detected to contain the skin color. As a result, a sufficiently high bitrate may not be assigned to those macroblocks not detected to contain the skin color. Under such a circumstance, lack of a sufficiently high bitrate that can be assigned to the macroblocks not detected to contain the skin color leads to degraded image quality, resulting in deteriorated image quality as a whole despite improved image quality of the skin color.
Therefore, Japanese Patent Laid-Open No. 2005-80151 (hereinafter referred to as Patent Document 1) proposes a method for maintaining the overall image quality. This method does so by not assigning a higher bitrate to those macroblocks detected to contain the skin color if the number of such macroblocks of all the macroblocks across the screen exceeds a given number.